Creating a torus with more than 256 segments with nearly 1km radius?
Start by adding a circle, with 360 vertices, a radius of 50, and the Fill Type set to Nothing.

In edit mode rotate the circle along the Y axis by 90°. Then move the circle 900 along the Y axis.

Last add a Screw modifier, with Steps and  Render Steps set to 1800. Leave all other modifier settings to default.

You now have a torus with 648,000 vertices and faces; 1800 major segments and 360 minor segments.